Oleum Zingiberis. - Ingwerol. - Essence de Gingembre.

Origin and Production. The original home of Zingiber officinale, Roscoe (Amomum Zingiber, L.), is southern Asia. On account of its spicy rhizome, it is cultivated there as well as in the islands of the South Asiatic archipelago, in Japan, the West Indies and Africa. Arranged according to the amounts shipped2), ginger is exported from the following countries: China, India, Japan, Jamaica, Sierra Leone. Concerning its cultivation in East Africa, which has been undertaken recently, Prof. Dr. Zimmer-mann3) makes the following statement:

Ginger makes rather high demands on the fertility of the soil, which must not be too firm, neither too marshy. A sandy clay containing lime is best adapted for the cultivation of ginger. New plants are started exclusively from cuttings of the rhizomes. These are stored in a dry place, and shortly before planting, are cut into pieces, each of which is 3 to 5 cm. long and must contain at least one bud. The arrangement of the fields is like that of the potato field; the ridges should preferably have a width of 30 cm., the furrows one of 70 cm. The cuttings of the rhizome are planted in the ridges at a distance of from 25 to 30 cm. in holes 7 to 10 cm. deep. These holes should be well filled up with earth, for the roots that lie in cavities are said to rot easily.

1) Verslag 's Lands Piantentuin te Buitenzorg 1897, 36.

2) For statistical data concerning the commerce in ginger see Bull. Imp. Inst. 10 (1912), 118; Report of Schimmel & Co. October 1912, 66.

3) Mitteilungen aus dem Biologisch-Landwirtschaftlichen Institut Amani July 2nd 1904. No. 28. Reprint from the Usambara Post.

The harvest begins when the overground portion has dried, i'. e. as a rule after 9 to 11 months. The rhizomes are dug up, carefully washed, and all roots removed. From this stage onward, the treatment varies according to whether the ginger is to be dried or preserved. With regard to the dried rhizome, a further distinction is made between peeled or white ginger, and unpeeled or black ginger.

If the ginger is to be peeled, only a very thin layer of skin should be removed, for the aromatic constituents are deposited just beneath the epidermis. As soon as peeled, the rhizomes are again placed in pure water, where they remain over night, after which they are dried. Since great stress has been laid on a white color for peeled ginger, attempts to improve thereon by means of chlorinated lime and gypsum have been made. Such practices, however, are to be discouraged.

The unpeeled ginger is dried immediately after careful cleaning.

The output of a ginger field averages about 1100 to 1700 kg. per hectare; in exceptional cases 2200 kg. per hectare are harvested. The ginger plants greatly exhaust the soil, so that repeated cultivation in the same field is possible only with much fertilization.

When distilled, dried ginger yields on the average 2 to 3 p.c. of volatile oil. Some varieties yield less. Thus e.g. a Japanese ginger yielded but 1,23 p.c, a Jamaica ginger 1,072 p.c.1) and a Cochin ginger 1,5 p.c.2).

Properties. Ginger oil has the aromatic, not very strong, but persistent odor of ginger, without, however, possessing its pungent taste. It is greenish-yellow in color and somewhat viscid. d16o 0,877 to 0,886. However, individual oils, both lighter and heavier have been observed; aD - 28 to - 50°, but oils with lower angles appear to occur; A. V. up to 2; E. V. 0 to 15; E. V. after acetylation 33 to 42. Ginger oil is difficultly soluble in alcohol: of 95 p.c. alcohol up to 7 vols, are required and even then the solution is not always clear; even in 90 p.c. alcohol some of the oils are not completely soluble no matter how many volumes are used.

1) H. Hasnsel, Pharm. Ztg. 48 (1903), 58.

2) H. Haensel, Apotheker Ztg. 20 (1905), 396.

An oil obtained from Japanese root differed from that commonly distilled from the African and Jamaica drug. However, it could not be regarded as a perfectly normal oil, since it had resulted from a trial distillation of but a few kilograms of ginger. It had the high specific gravity of 0,894. Contrary to the commonly observed laevorotation, it was dextrogyrate,aD + 9° 40'. It was soluble in even 2 vols, of 90 p.c. alcohol and showed no reaction for phellandrene.

Another oil prepared in Japan1) revealed properties which did not differ from those of the ordinary oils: d15o 0,883; aD - 26°52'. With sodium nitrite and glacial acetic acid it gave a very distinct reaction for phellandrene.

An oil distilled in the Philippines with a yield of 0,072 p.c. (presumably from fresh root) revealed the following properties as determined by R. F. Bacon2): d30/30o0,8850; aD30o5,9° (-{-?); nD30o 1,4830; S. V. 14. The oil was light yellow in color and soluble in twice its volume and more of 90 p.c. alcohol.

Composition3). The lower boiling fractions of ginger oil contain terpenes. The angle of rotation of fraction 155 to 165° is opposite to that of the oil itself, viz., +63° 13'. This fraction contains d-camphene4). When treated with acetic acid and sulphuric acid there results an acetate, which upon saponification yields isoborneol (m. p. 212°; m. p. of bromal derivative 71°). The fraction boiling about 170° contains B-phellandrene4) (m. p. of nitrite 102°).

1) Report of Schimmel & Co. October 1893, 50.

2) Philippine Journ. of Sc. 5 (1910), A, 259.

3) The older investigations threw no light on the chemical composition of the oil. Papousek, Sitzungsberichte der Akademie der Wissenschaften zu Wien 9 (1852), 315; Liebig' s Annalen 84 (1852), 352. - J. C. Thresh, Pharmaceutical Journ. III. 12 (1881), 243.

4) Bertram and Walbaum, Journ. f. prakt. Chem. II. 49 (1894), 18.

So far as the aroma is concerned, an important part of the oil are three oxygenated constituents observed by Schimmel & Co.1), viz., cineol, citral and borneol. Fraction 170 to 175°, distilled under ordinary pressure, yielded, upon the addition of iodol, considerable amounts of the iodol addition product of cineol (m. p. 112°).

A fraction boiling between 90 and 105° (5 mm.) became solid and on being drawn off yielded crystals of a borneol-like odor which, after recrystallization from petroleum ether, melted at 204°. Additional amounts of borneol as well as a small amount of an alcohol, with the odor of geraniol, were obtained by treating the liquid drained from the borneol referred to above, with phthalic acid anhydride in benzene solution. The alcohols obtained from the acid phthalic acid esters upon saponification with alcoholic potassium hydroxide, remained liquid in part. Hence, in addition to borneol, there must have been present another alcohol, possibly geraniol. After re-crystallization from light petroleum, the free bornylphthalic acid melted at 164°. Fractions 90 to 122° (5 mm.) also contained citral, which was separated as a solid addition compound by shaking with a concentrated solution of sodium bisulphite. Regenerated with soda solution, it was converted into citryl-B-naphthocinchoninic acid melting at 179°.

Upon fractionation of the saponified ginger oil, H. von Soden and W. Rojahn2) obtained a new sesquiterpene, the zingiberene, which has the following properties: d16o 0,872; aD - 69°. Under atmospheric pressure it distils at 269 to 270° with slight decomposition; under 14 mm., at 134°. Elementary analysis yielded results agreeing with the formula C15H24.

O. Schreiner and E. Kremers3) prepared several characteristic derivatives of zingiberene which have been described in Vol. I, p. 329.

From the first fraction of ginger oil v. Soden and Rojahn isolated an aldehyde with the aid of bisulphite. However, the amount was too small for a more minute examination.

1) Report of Schimmel & Co. October 1905, 38.

2) Pharm. Ztg. 45 (1900), 414.

3) Pharmaceutical Archives 4 (1901), 63.

In Jamaica ginger oil F. D. Dodge1) found a small amount of an aldehyde which is probably n-decylic aldehyde.